JPH05257514A - Machine compensation method, and machine compensation system and program for computer numerical control machine - Google Patents

Abstract

(57) Abstract: A machine compensation system, method and computer program for a computer numerical control (CNC) machine are provided. A machine compensation system, a method and a computer program according to the present invention calculate a linear displacement and an inclination of a center line CL of a work piece with respect to a rotation axis B of the machine when rotating a work piece 220 to be cut on a CNC machine. Evaluate automatically. The system, method and program according to the present invention provide a compensation amount that corrects for any misalignment of the workpiece axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary machine tool having a high degree of freedom of movement for cutting an object (hardware) mounted on a rotatable table top plate, and particularly to a reference rotary axis of the machine. The present invention relates to a rotary machine tool having a large degree of freedom of movement, which automatically evaluates the inclination of the center line of an object and the linear displacement alignment, calculates the compensation amount of each, and performs accurate cutting.

[0002]

2. Description of the Related Art Computer numerical control (CNC = Comput
er Numerically Controlled) machine is capable of accurately cutting an object and manufacturing the object (workpiece) with a tolerance of about 3/1000 inch (0.003 ″). Conventionally, it is a component of a CNC machine. Methods and devices for manually assessing alignments have been used, and automatic tool length compensation to compensate for tool length and diameter have also been used.Many CNC machines use rotary tools to hold an object during cutting. Such machines are often used in automated factories, where automated general purpose production systems (FMS = Flexible M) are used.
For various cutting operations, an automated guiding vehicle reciprocates an object mounted on a pallet from machine to machine or to different machine cells, as in the anufacturing system).

Objects are typically loaded into fixtures used on pallets and moved to final position using mallets and dial indicators. Positioning the object in the fixture in this manner achieves the desired coaxiality. This may require loosening or resetting the object. This method cannot correct tilt errors observed as differences in the amount of eccentricity at different heights of the object. Moreover,
The pallet alignment system at multiple workstations in an automated FMS cannot maintain the degree of matching required to make pallets compatible. Manual realignment of settings, where each workstation assigns a setting to that workstation, is not practical for this environment.

Accordingly, it is highly desirable to develop a cutting technique that provides a method for automatically cutting an object loaded in a fixture without the intervention of an operator to manually position the object.

[0005]

SUMMARY OF THE INVENTION The present invention is a computer numerical control (CN).
C) Provide a system and method for automatically, accurately and repeatedly evaluating the geometrical conditions of an object mounted in a fixture on a machine pallet with respect to various degrees of freedom of motion of the object. The present invention provides a computer means for a CNC machine having a probe mounted on a spindle for measuring the relative position of an object mounted on a rotatable mount and measuring the object relative to the axis of the rotatable mount. Evaluate the state of the object with respect to the linear displacement and tilt of the axis of. The present invention is an apparatus, method, and CNC in a machine-readable medium.
A computer program in the form of machine-readable instructions for a machine is provided. INDUSTRIAL APPLICABILITY The present invention can be used for a multi-axis machine tool having a rotary shaft, for example, a CNC drill, a milling machine and a machining center. In a preferred embodiment of the invention, computer means are provided for controlling the machine,
A calculation is performed to evaluate the state of the object, a calculation is made to estimate the machine axis offset from the evaluated state, and then the machine axis offset is automatically adjusted based on these calculations.

To evaluate the state of an object, computerized control means directs a probe mounted on the spindle,
By measuring at least two different positions of the object and using the measured positions to calculate the geometrical alignment of the object with respect to one of the degrees of freedom of movement of the object. The above-mentioned features and other effects of the present invention will be described below with reference to the drawings.

[0007]

[Concrete configuration] FIG. 1 shows a structure such as T-30 manufactured by Cincinnati Milacron.
An axial multipurpose milling, drilling, boring machine tool type computer numerical control (CNC) machine 6 is shown.
The CNC machine 6 is generally constructed around a column 8 mounted on a linearly movable machine base 12 which is slidably mounted on a horizontal X-direction guideway 16 parallel to the X-axis. The CNC machine 6 functions to position the spindle mechanism 10 with respect to a worktable (work table) 11 that can be positioned, supply power to the spindle mechanism 10, and control the power. A spindle mechanism 10 powered by a machine motor (not shown) includes a tool holder 14 configured to receive and hold various cutting tools, measuring devices and probes used in a cutting process. ..

The CNC machine 6 spins the tool mounted on the tool holder 14 of the object mounted on the work table 11 at a specific position, that is, a workpiece (shown in FIG. 2). A means for moving the spindle mechanism 10 is provided. Workpiece and rotating spindle mechanism 10
Relative positioning between and is carried out along three linear movement axes X, Y and Z and around two axes of rotation, namely trunnion axes A and B, as indicated by the corresponding reference axes in FIG. Be seen.

The CNC machine 6 has a spindle carrier 22 and the spindle mechanism 10 is mounted on the carrier 22 by a trunnion, so that the trunnion angle a = 0 °.
The spindle mechanism 10 parallel to the Z-axis is the trunnion axis A
Can be pivoted around. The spindle carrier 22 is
It is slidably mounted on a vertical or Y guide path 30 mounted on the column 8 so that the spindle mechanism 10 can move along the Y axis.

A horizontal Z-direction guide path 36 slidably supports the work table 11, and the work table 11 is slidably supported.
Is a table top 44 rotatable about a vertical table axis B which is parallel to the Y axis when properly aligned.
have. The present invention, in the preferred embodiment, is designed for use with objects mounted on movable pallets (shown in FIG. 2). The movable pallet is the top plate 44
The top plate 44 may be referred to as a clamp plate when used for fixing the movable pallet.

Further, in FIG. 1, the CNC machine 6 is provided with an automatic tool changing mechanism 70. The exchange mechanism 70 is of a type commonly used in the art and is configured to store the trigger probe 74 used in the present invention. The computerized controller 64 that controls the CNC machine 6 has a display 68 and is typically mounted near or near the post 8 and work table 11. Computerized controller 64
In accordance with the present invention, is provided with computer means for evaluating the geometrical condition of the work piece and calculating tool point compensation for compensating for misalignment of the object during cutting of the object.
The program can be CNC tape or direct numerical control (DNC).
= Direct Numerical Control) methodology is used to load (load) in the usual way.

The probe (exploration) technique used in the present invention is
Related US patent application entitled “Automated Maintenance System for Computerized Numerical Control Machines” by Inventor R. David Hemmerle, et al., Assigned to the applicant (Applicant's ref. 13DV-107
19). As shown in FIG. 2, the movable pallet 200 is equipped with a fitting 210 for fixing an annular object 220 such as a gas turbine engine case section on the top of the movable pallet 200. It can be attached to the top plate 44. The rotation axis of the pallet 200 is the table axis B of the machine 6 in FIG.
Is set to match. Further, referring to FIG. 2, the present invention is provided with means for probing the annular object 220 having the object centerline CL with the probe 74. The object centerline CL has an offset and skew relationship with respect to the centerline of cutting, that is, the table axis B.

FIG. 3A shows a table axis B and an object center line C.
The degree or magnitude of the linear offset DR with respect to L is shown. The difference is exaggerated compared to the object height DY for the object 220 shown fixed to the fixture 210 mounted on the pallet 200. In FIG. 3B, the degree or magnitude of the tilt is shown as the tilt angle E between the table axis B and the object center line CL. Also for convenience of illustration, the object height DY for the object 220 shown fixed to the fixture 210 mounted on the pallet 200.
The difference is exaggerated compared to. Also shown are the axial top position TL and bottom position BL, which are located along the axis B at a distance P155, which are the positions to probe the object 220 in accordance with a preferred embodiment of the present invention. ..

Referring to FIG. 4, the top position (FIG. 3 (B)
TL), four circumferential stations S1, S arranged at b = 0 °, 90 °, 180 ° and 270 ° respectively around the axis B of the rotary table of the machine.
2, S3 and S4, the probe 74 is used to
The geometric state of the object centerline CL is evaluated by exploring the side surfaces of 20. Thereby, the computer means, as shown in FIGS. 6 and 7, the eccentricity P1 at the top.
The inclination direction P151 of the eccentricity at the top of 50 and the top center TCL of the object center line is calculated. The same calculation is performed for the object center line CL at the bottom position (BL in FIG. 3 (B)) located a distance P155 away along the axis B, and as shown in FIG. 6 and FIG. The eccentricity size P152 and the eccentric inclination direction P153 at the bottom of the bottom center BCL of the object center line are calculated.

Using the parameters measured and calculated by probing, the offset is geometrically generated as a function of the Y machining coordinate along the Y axis of the machine, eg according to the CNC subroutine below. The CNC Subroutine is an NC which represents the preferred embodiment of the offset calculation of the present invention.
It is a code list and is subject to copyright protection. The geometric and vector relationships of the subroutine are shown in FIGS.

The copyright owner does not object to the copying and reproduction of the patent specifications by others as long as they appear in the patent package or the official gazette of the Patent Office, but otherwise, all copyrights are reserved. Withhold. CNC Subroutine: (ID, GSUB, RCOMP, DISPLACEMENT & INCLINATION COMPENSA
TION) P18 = (PRGPSN (Y) + ((P21 + 12.5) * (SIND (PRGPSN (A))))) P10 = (ABS (P151-P153)) (IF (P10) <> 0 GOTO N020) P89 = (P153) P88 = (P152 + (((P18-P154) / P155) * (P150-P152))) (GOTO N160) N020 (IF (P10) <180 GOTO N040) P10 = (360- (ABS (P151 -P153))) N040 P11 = (ATAND ((P150 * (SIND (P10))) / (P152- (P150 * (C
OSD (P10)))))) P12 = ((P150 * (SIND (P10))) / (SIND (P11))) P13 = (((P18-P154) / P155) * P12) P17 = (P13- (P152 * (COSD (P11)))) (IF (P17) <> 0 GOTO N070) P17 = .00001 N070 P14 = (ATAND ((P152 * (SIND (P11))) / (P17))) (IF (P14)> 0 GOTO N090) P14 = (180 + P14) N090 P88 = ((P152 * (SIND (P11))) / (SIND (P14))) P15 = (180- (P11 + P14)) P16 = (P153 + 180-P151) (IF (P16) <360 GOTO N130) P16 = (P16-360) N130 (IF (P16)> 0 GOTO N140) P16 = (P16 + 360) N140 (IF (P16) <180 GOTO N150) P15 = (P15 * -1) N150 P89 = (P153 + P15) N160 (STO, 55, SOV (Y), 0) (STO, 55, SOV (X), ((SIND (P89-PRGPSN ( B))) * P88)) (STO, 55, SOV (Z), ((COSD (P89-PRGPSN (B))) * P88)) G55 (END, GSUB) I explained the principle,
It is obvious that various changes and modifications can be made to the above-described embodiments without departing from the scope of the present invention as set forth in the claims.

[Brief description of drawings]

FIG. 1 is a perspective view showing a CNC machine according to a preferred embodiment of the present invention together with a reference coordinate system.

2 is a perspective view showing an object mounted on a rotatable table top of the CNC machine of FIG. 1. FIG.

3 is a diagrammatic lateral cross-sectional view of the object of FIG. 2, with FIG. 3 (A) showing axis offset and FIG. 3 (B) showing axis skew.

FIG. 4 is a diagrammatic cross-sectional view from the top of the object of FIG. 2 taken in the upper position.

5 is a diagrammatic sectional view from above of the object of FIG. 2 seen in the lower position.

6 is a diagrammatic perspective view of a vector diagram showing the centerline position of the object of FIG. 2. FIG.

7 is a diagrammatic perspective view of a vector diagram illustrating the centerline offset calculation for cutting the object of FIG. 2 at the Y coordinate.

[Explanation of symbols]

 6 CNC machine 10 Spindle mechanism 11 Work table 12 Machine base 14 Tool holder 44 Table top plate 64 Computerized controller 70 Tool change mechanism 74 Probe 200 Pallet 210 Fixture 220 Object

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Earl David Hemar No. 9633, Lansford Drive, Blue Ash, Ohio, United States

Claims (8)

[Claims] 1. A machine tool for evaluating linear displacements and tilts of a centerline of an object with respect to the axis of rotation of a machine and compensating for the evaluated linear displacements and tilts as a function of coordinates associated with the axis of rotation of the machine. A machine compensation method comprising the step of generating a point compensation function in the computer means of the machine. 2. The evaluation step comprises the step of determining the position and orientation of the centerline of the object by exploring the object with a probe mounted on a machine spindle. Machine compensation method. 3. The probe uses the probe at four equiangular positions around the object for two different positions along the coordinate associated with the axis of rotation of the machine. Machine compensation method described in. 4. A machine compensation system for a computer numerically controlled (CNC) machine, said means for evaluating linear displacement and tilt of a centerline of an object with respect to an axis of rotation of the machine, the machine in a computer means of said CNC machine. Means for generating a tool point compensation function, the machine tool point compensation function calculating a machine tool point compensation for the evaluated object centerline as a function of coordinates associated with the axis of rotation of the machine. A mechanical compensation system characterized in that it operates as described above. 5. Machine compensation according to claim 4, wherein the means for assessing the position and orientation of the centerline of the object comprises means for probing the object with a probe mounted on the spindle of the machine. system. 6. The probe means explores with the probe at four equiangular positions around the object for two different positions along the coordinates associated with the axis of rotation of the machine. 5. The mechanical compensation system according to item 5. 7. A program for a computer numerical control (CNC) machine for cutting an object, which evaluates linear displacement and tilt of a centerline of the object with respect to a rotation axis of the machine and is associated with the rotation axis of the machine. A machine for directing a probe mounted on the machine spindle to generate a volatile machine tool point compensation function in the machine's computer means for compensating for the evaluated linear displacement and tilt as a function of the measured coordinates. A program for a computer numerical control machine, characterized by having readable instructions. 8. The machine readable command for exploration uses the probe at four equiangular positions around the object for two different positions along the coordinates associated with the axis of rotation of the machine. 8. The program according to claim 7, which includes a command to search by.